We went on vacation and shut our Intermatic Electronic Water Heater Timer WH21 off, so my daughter wouldnt have a problem in case the power wemt out. We came home and resumed the timer after setting the time, it now does not work, the timer doesnt move. Do you have any suggestions, we bought the timer in April, which makes it 5 months old

Only parts sold for WH21 timer are clock motor and tripper.
You might be able to find something on ebay... like old non-functioning timer
http://waterheatertimer.org/How-to-troubleshoot-Intermatic-WH21-timer.html

Gene

Water Heater Timers Save Money

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

Copy following link for Wh21 manual, troubleshoot walk-thru, and replacement tripper identification.
The red light is a power indicator, and this indicates that timer has 240Volt (208-250Volt) power available, but does not indicate if water heater is ON or OFF.
http://waterheatertimer.org/How-to-troubleshoot-Intermatic-WH21-timer.html

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

You posted under WH21 Intermatic timer.
Intermatic does not show parts for that timer except 156EB1945A tripper.
http://waterheatertimer.org/Intermatic-trippers-and-parts.html

You might have your Line and Load wires reversed.
Line wires come from circuit breaker.
Load wires go to water heater.
http://waterheatertimer.org/B220C.html

WH21 wiring: There are 2 Hot Line wires coming from breaker box that connect to terminals 1 and 2.
WH21 is SPST and turns off one Hot wire going to Load. So Load wires connect to terminals 2 and 3. Terminal 2 has 2 wires: 1 Line wire and 1 Load wire.
http://www.intermatic.com/~/media/files/intermatic/products/instructions/timers/wh21%20-%20english.ashx

Keep in mind that WH21 is 25 amp, 2Hp 240Volt timer that will work on water heaters up to 4500 watts. Look at label on side of tank to see wattage. All appliances and motors have labels.
http://waterheatertimer.org/Figure-Volts-Amps-Watts-for-water-heater.html

Larger wattage water heaters require 30 amp water heater timers as shown following page:
http://waterheatertimer.org/Boxtype.html

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Also take advantage of fixya expert assistance live.
For a price, expert works with you via e-mail while you work on timer or any do-it-yourself project.
Fixya is always less expensive than a service call.

Parts are not available for WH21 240V water heater timer.
Timer has 1 year limited warranty.
http://www.intermatic.com/customer%20service/frequently%20asked%20questions.aspx
WH21 is rated for 25Amps and works on water heaters up to 4500Watts.
Look at label on side of tank to see wattage.
WH21 is SPST and turns off one hot wire to water heater.

I ran a business for many years.
Cost of stocking, organizing, and shipping parts is near same cost as new timer.

Following page shows selection of replacement timers:
http://waterheatertimer.org/Boxtype.html

For example, I have tested WH40 and T104 and other timers that show on page.
Trippers and motors are available for Intermatic box timers WH40 and T104, so you can maintain these specific models for many years.
http://www.grainger.com/Grainger/timer-accessories/timers/electrical/ecatalog/N-8hi
WH40 and T104 timers are SPDT and turn off both hot wires to water heater.
Both timers will work on any wattage residential water heater

http://waterheatertimer.org/How-to-wire-T104-Intermatic-timer.html
http://waterheatertimer.org/How-to-wire-EH40-hot-water-heater-timer.html

You probably have defective timer.
I test timers, and some timers arrive defective.
I have not tested WH21, so check with your friend about the indicator light.

Mechanical dial timers make audible noise, and dial should rotate as time passes and keep exact time. If dial is not rotating correctly on new timer, then something is not working correctly. The level of timer is not an issue. It sounds like the motor gear is not engaging with dial.
To test timer noise, click manual override lever. You will hear same noise each time timer turns on-off.

WH21 is SPST 21amp timer which turns off one hot wire to water heater.
WH21 is rated to work on 4500Watt 18.75 amp water heater. Or smaller wattage.
Check label on side of water heater for wattage. WH21 is not rated for 5500Watt water heater.

There are many water heater timers:
Electronic timers give more precise time control and option for shorter on-off periods.
Electronic timers are quieter and don't need to be reset after power outage.
http://waterheatertimer.org/Boxtype.html

More expensive Intermatic WH40 timer is rated for greater capacity, and has replacement motors and trippers. WH40 is noisy too, but will last for years. WH40 is SPDT so it turns off both hot wires to water heater. I prefer SPDT, and have tested WH40 and other timers shown on link above.
To order extra parts for WH40:
http://www.grainger.com/Grainger/timer-accessories/timers/electrical/ecatalog/N-8hi

Add a comment for more free help.
Also take advantage of fixya expert assistance live.
For a price, expert works with you via e-mail while you work on timer or any do-it-yourself project.
Fixya is always less expensive than a service call

1) WH21 manual does not say if indicator lights up when Load is ON. That says indicator lights up when timer has power.
2) Flip manual control to reverse program and see if light stays on or goes off.

3) GE15207 water-heater-timer has two different indicator lights. One is ON when timer has power. The other is ON when Load has power. But GE timer has NO and NC terminals.

4) The reason I answered this question is that folks have problems wiring timers and then ask questions trying to piece together why timer is not working.
5) If timer is not functioning as expected, read below, or add a comment with details about your wiring.

6) Wiring WH21
240V circuits have 2 hot leads.
Hot leads from breaker connect to center terminal and to left terminal.
Leads going to Load (water heater) connect to center terminal and to right terminal
If you have leads from breaker and leads to Load reversed, timer will not function except when manual control is switched ON.
In this case, reverse wires on right and left terminals.

Go to intermatic.com/.../instruction%20manuals.aspx scroll down to your model number and click and there you are

The clock motor might have gone bad.
Open following link for WH21 troubleshoot
http://waterheatertimer.org/How-to-troubleshoot-Intermatic-WH21-timer.html

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

There is a short. The timer mechanism is mechanical, so the problem is not failed electronics.
The WH21 is for 240 volt circuits, so it has 2 hot wires and 1 ground from the breaker box. Only one hot line to the water heater is turned off, but both lines are attached to screw terminals at timer.
To see if the problem is a shorted element or shorted wire in water heater, disconnect hot leads to water heater one at a time, and then test. Then disconnect ground wire from water heater and test again. Then disconnect all wires to water heater, and test again.
If the problem is in the water heater, search for troubleshooting steps on internet. Focus on testing elements.
If the problem is not in the water heater, then a frayed wire on back of timer is next checkpoint. The timer motor is the final suspect. You can detach the timer motor from the housing, and test for stray voltage. Intermatic WH21 is inexpensive to replace.